Manufacture of fibers from thermoplastic material, particularly glass fibers



ETAL 3,084,525 FROM HERMOPLASTIC RLY GLASS FIBERS 22, 1960 April 1963 M. LEVECQUE MA ACTURE OF FIBERS ERIAL, PARTICULA Filed Jan.

INVENTORS MAUP/C' ('HAzPPEA/Wf'fl BY W4 fl ATTORNEY ilnited States Patent G 3,084,525 MANUFACTURE OF FIBERS FROM THERMO- PLASTIC MATERIAL, PARTICULARLY GLASS FEBERS Marcel Lvecque, Saint-Gratien, and Maurice Charpentier, Rantigny, France, assignors to Compagnie de Sfilllt-Gb3lll, Neuilly-sur-Seine, France, a corporation of France Filed Jan. 22, 1960, Ser. No. 4,085 Claims priority, application France Jan. 27, 1959 8 Claims. (Cl. 656) The present invention relates to a process of manufacturing fibers from thermoplastic material, particularly glass fibers, in which the material in the melted state, contained in a hollow rotating body provided with orifices on its periphery, is projected through these orifices in the form of threads by the action of centrifugel force. It is already known that in order to produce fibers of great fineness, the threads should be subjected to gaseous currents at high speed, in particular gaseous currents resulting from the expansion of gases leaving a combustion chamber.

To effectuate the process, the centrifuge body may have one or several rows of projection orifices in its peripheral wall or band. In order to attain efficient industrial production, it is desirable to increase as much as possible the number of rows of orifices, which, of course, tends to increase the height of the peripheral wall of the centrifuge. When the number of these rows is considerable, for example, exceeding twenty, various difficulties in obtaining fibers of good quality are encountered.

' It is the object of the present invention to provide an improvement which permits the obtaining of fibers of very high quality, no matter how many rows of projection orifices there are, that is, no matter what may be the height of the peripheral band of the hollow rotating body.

This improvement consists in introducing a combustible element, in the gaseous, solid or liquid state, into the gaseous current which passes along the peripheral band to effect with certainty the drawing out of the threads of thermoplastic material. This introduction of the combustible element is effected in a manner to attain a combustion in the zone surrounding the rotating body and along a predetermined height of the latter. By virtue of the present invention, the continuous release of calories realized by this combustion allows obtaining fibers of very good quality, even by the use of a rotating body with a large number of rows of orifices, which may be in excess of twenty.

This advantageous result can be explained as follows:

When a gaseous current is passed along the peripheral band, its speed maintains an acceptable value over its entire height, while on the other hand, the temperature, by reason of the induction of cold gases, is lowered very rapidly. The result is that, for peripheral bands or walls of relatively great height, the temperature of the gaseous current becomes too low in the zone near the lower rows of orifices to adequately maintain the necessary conditions for good attenuation or drawing-out of the filaments. In accordance with the invention, by causing the introduction of a combustible element in the gaseous current, this element entering into combustion more particularly toward the lower part of the peripheral hand, because of the presence in said current of a greater quantity of comburent resulting from the induction of outer air, a release of heat is realized in this part which maintains the gaseous current at the desired temperature for the drawing-out action.

It should be observed that, contrary to what might be supposed, it is not possible to obtain the desired results by using gases containing non-combustible elements by acting solely on the ratio of the comburent-combustible moplastic material ice mixture admitted into the combustion chamber. If one operates in such a manner serious drawbacks would be encountered. In particular, the band would be in a reducing medium which would bring about its deterioration. Moreover, the temperatures of the gases are imposing and if one works in a reducing medium they would be much too high, particularly toward the upper part of the band. Therefore, it is necessary to operate with a considerable excess of air which permits maintenance of an oxidizing atmosphere in the vicinity of the peripheral band.

According to one method of practicing the process according to the invention, the combustible element may be in a solid state, for example, in the form of non-combustibles in the combustion chamber wherein is produced the attenuating gaseous current, these particles being carried along by said gaseous current.

According to another method of operation, the combustible element is constituted by a certain quantity of combustible gas which may be introduced into the cornbustion chamber and which is carried along by the burned gases through the expansion orifices.

Several forms of realization of devices for putting the invention into operation are described below by way of example, and are illustrated in the accompanying drawing wherein FIG. 1 is a vertical sectional view of the left end of a rotary centrifuge with the overlying combustion chamber for directing a blast of gaseous current transversely to fibers discharging from the centrifuge to efiect the at tenuation thereof, and which includes an arrangement for introducing a non-combustible element into the gaseous blast for combustion at a later time;

FIG. 2 is a vertical sectional view of an assembly similar to that shown in FIG. 1 illustrating a different mode of introducing the non-combustible element into the gaseous stream; and

FIG. 3 is a vertical sectional view of a still different embodiment of the invention as applied to a rotary centrifuge and overlying combustion chamber.

In the embodiment shown in FIG. 1, the combustion chamber 1 is preceded by a chamber 2 for mixing the combustible and the comburent, said chambers communicating by a grid 3. The combustion chamber is annular and its orifice 4, which may be a continuous slot or made up of orifices close together, is placed in the usual manner so that the gaseous current 6 at high temperature which escapes from it traverses across band 5 of the rotating body C along its entire height. As shown, the band 5 is provided with a plurality of superposed rows of orifices for projecting therethrough molten ther which is thrown against the inner face of this wall by centrifugal force and other Ways known in the art.

In accordance with the invention, a supplementary combustible inlet feeder F, in the form of a conduit, is provided near grid 3. The combustible may be fed in the form of solid particles such as carbon. This combustible may also be a gas of high heating power, with a hydrocarbon base, such as propane, ethane, butane, for example. This contribution of supplementary combustible carries a non-uniform mixture of combustible-comburent into the combustion chamber. Under the effect of the combustion temperature in said chamber, cracking is produced leading to the formation of particles of carbon which leave orifice 4 unburned. These carbon particles are carried along by the combustion gas and burn during the passage along band 5, and particularly toward its lower part.

In the example shown in FIG. 2, the supplementary introduction of combustible material is efiected near the exit of the combustion chamber through channel 8. Be-

cause of its very brief passage in the combustion chamber, this combustible material does not have time to burn. Its combustion does not take place until it practically passes in front of the band.

In the embodiment shown in FIG. 3, the combustion chamber 1 is not preceded by a mixture chamber. The combustible arrives by a discharge tube 9 and the primary air arrives itself under pressure through an annular passage 10 concentric with discharge tube 9. Also, a space 11 is provided between passage 10 and the inlet orifice of the combustion chamber so as to permit the admission of induced air through this space. The jet of combustible mixes very rapidly with the primary air. This mixture carries along the secondary air coming from 11 which mixes only very progressively. The formation of non-combustible solids takes place at the inlet of the combustion chamber which leave by orifice 4 with the mixture of burned gases and air, which solids burn subsequently adjacent the lower end of the peripheral wall 5.

It is desirable, as shown in the drawings, to make the lips of the slots or orifices of metallic pieces which contain passages P for the circulation of a refrigerating fluid.

We claim:

1. The method of manufacturing fibers from heated viscous thermoplastic material, which comprises projecting the heated viscous material by centrifugal force from the peripheral wall of a rapidly rotating body having a plurality of rows of orifices therein through which the viscous material issues in filamentary form, directing hot combustion gases into the atmosphere transversely to planes of emission of the fibers in contact with the peripheral wall along the entire height thereof from the topmost to the lowermost row of orifices, to entrain therein the fibers issuing from all the rows of orifices, and intermixing combustible material with said combustion gases before said gases enter the atmosphere, said combustible material adapted to travel with said gases past said peripheral wall and to burn in the course of such travel to maintain the temperature of said gases substantially constant along the entire height of said peripheral wall.

2. An apparatus for producing fibers from thermoplastic material comprising a centrifuge having a peripheral wall provided with a plurality of rows of orifices for discharging the material therethrough by centrifugal force, a. combustion chamber adjacent to and surrounding said peripheral well, said combustion chamber having means for supplying thereto a combustible mixture and provided with an annular outlet opening located in the immediate vicinity of the topmost row of orifices for directing hot combustion gases into contact with the peripheral Wall, along the entire height of said wall, and separate means connected to said combustion chamber for feeding additional combustible material thereinto for intermixture with said hot combustion gases before said gases leave the outlet opening of said combustion chamber to form combustible particles adapted to travel with said combustion gases past said peripheral wall for progressive combustion therealong to maintain the temperature of said gases substantially constant along the entire height of said peripheral wall.

3. The method of manufacturing fibers from heated viscous thermoplastic material, which comprises projecting the heated viscous material by centrifugal force from the peripheral wall of a rapidly rotating body having a plurality of rows of orifices therein through which the viscous material issues in filamentary form, directing an annular blast of hot combustion gases into the atmosphere transversely to planes of emission of the fibers in contact with the peripheral wall along the entire height thereof from the topmost to the lowermost row of orifices, to entrain therein the fibers issuing from all the rows of orifices, and intermixing combustible material with said combustion gases before said gases enter the atmosphere to form combustible particles adapted to travel with said gases past said peripheral wall for progressive combustion therealong to maintain the temperature of said combustion gases substantially constant along all levels of the orifices through which the filaments are projected.

4. The method of manufacturing fibers as set forth in claim 1 wherein the added combustible material is in the form of hydrocarbon fluids subject to cracking by the combustion gases leaving a residue of carbonaceous material for subsequent combustion adjacent to the peripheral wall.

5. An apparatus as set forth in claim 2 wherein said last-mentioned means comprises a conduit for the com bustible material feeding into the combustion chamber .for discharge therefrom with the combustion gases.

6. An apparatus as set forth in claim 2 wherein said last-mentioned means comprises a conduit for hydrocarbon fiuid subject to cracking having the outlet thereof in said combustion chamber, to form a carbonaceous residue discharged with said combustion gases for subsequent combustion adjacent to said peripheral wall.

7. An apparatus as set forth in claim 2 wherein said last-tmentioned'means comprises a conduit feeding a com bustible gas into the outlet of said combustion chamber for discharge therefrom together with the attenuating combustion gases int-o'the space adjacent to said peripheral wall.

8. An apparatus for producing fibers from the thermoplastic material comprising a centrifuge rotating on a vertical axis and having a peripheral wall provided with a plurality of superposed rows of orifices for discharging the material therethrough by centrifugal force, a combustion chamber above said centrifuge, an inlet for comburent and combustible in the lateral Wall of said combustion chamber comprising an inner tube for the combustible material surrounded by an annular conduit for primary air both having the discharge ends thereof spaced from the lateral wall of the combustion chamber for the induction of secondary air through said space, an annularly shaped outlet opening in said combustion chamber surrounding said peripheral wall and located in the immediate vicinity of the topmost row of orifices for discharging the resulting hot combustion gases from said chamber downwardly into contact with said peripheral wall to attenuate the fibers issuing therefrom, said combustible material fed into said inlet being in excess of that required for the production of the hot combustion gases within said combustion chamber so that unburned solids are interspersed Within said combustion gases in their traverse across said peripheral wall for delayed combustion thereat to attain a substantially uniform temperature along the entire height thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,609,566 Slayter et al Sept. 9, 1952 2,624,912 Heyrnes et a1. Jan. 13, 1953 2,921,342 Siefert et al Jan. 19, 1960 2,931,422 Long Apr. 5, 1960 FOREIGN PATENTS 794,319 Great Britain Apr. 30, 1958 

1. THE METHOD OF MANUFACTURING FIBERS FROM HEATED VISCOUS THERMOPLASTIC MATERIAL, WHICH COMPRISES PROJECTING THE HEATED VISCOUS MATERIAL BY CENTRIFUGAL FORCE FROM THE PERPHERAL WALL OF A RAPIDLY ROTATING BODY HAVING A PLURALITY OF ROWS OF ORIFICES THEREIN THROUGH WHICH THE VISCOUS MATERIAL ISSUES IN FILAMENTARY FORM, DIRECTING HOT COMBUSTION GASES INTO THE ATMOSPHERE TRANSVERSELY TO PLANES OF EMISSION OF THE FIBERS IN CONTACT WITH THE PERIPHERAL WALL ALONG THE ENTIRE HEIGHT THEREOF FROM THE TOPMOST TO THE LOWERMOST ROW OF ORIFICES, TO ENTRAIN THEREIN THE FIBERS ISSUING FROM ALL THE ROWS OF ORIFICES, AND INTERMIXING COMBUSTIBLE MATERIAL WITH SAID COMBUSTION GASES BEFORE SAID GASES ENTER THE ATMOSPHERE, SAID COMBUSTIBLE MATERIAL ADAPTED TO TRAVEL WITH SAID GASES PAST SAID PERIPHERAL WALL AND TO BURN IN THE COURSE OF SUCH TRAVEL TO MAINTAIN THE TEMPERATURE OF SAID GASES SUBSTANTIALLY CONSTANT ALONG THE ENTIRE HEIGHT OF SAID PERIPHERAL WALL.
 2. AN APPARATUS FOR PRODUCING FIBERS FROM THERMOPLASTIC MATERIAL COMPRISING A CENTRIFUGE HAVING A PERIPHERAL WALL OPROVIDED WITH A PLURALITY OF ROWS OF ORIFICES FOR DISCHARGING THE MATERIAL THERETHROUGH BY CENTRIFUGAL FORCE, A COMBUSTION CHAMBER ADJACENT TO AND SURROUNDING SAID PERIPHERAL WALL, SAID COMBUSTION CHAMBER HAVING MEANS FOR SUPPLYING THERETO A COMBUSTIBLE MIXTURE AND PROVIDED WITH AN ANNULAR OUTLET OPENING LOCATED IN THE IMMEDIATE VICINITY OF THE TOPMOST ROW OF ORIFICES FOR DIRECTING HOT COMBUSTION GASES INTO CONTACT WITH THE PERIPHERAL WALL, ALONG THE ENTIRE HEIGHT OF SAID WALL, AND SEPARATE MEANS CONNECTED TO SAID COMBUSTION CHAMBER FOR FEEDING ADDITIONAL COMBUSTIBLE MATERIAL THEREINTO FOR INTERMIXTURE WITH SAID HOT COMBUSTION GASES BEFORE SAID GASES LEAVE THE OUTLET OPENING OF SAID COMBUSTION CHAMBER TO FORM COMBUSTIBLE PARTICLES ADAPTED TO TRAVEL WITH SAID COMBUSTION BASES PAST SAID PERIPHERAL WALL FOR PROGRESSIVE COMBUSTION THEREALONG TO MAINTAIN THE TEMPERATURE OF SAID GASES SUBSTANTIALLY CONSTANT ALONG THE ENTIRE HEIGHT OF SAID PERIPHERAL WALL. 